JSc- EUSL(2008) Vol.5 No.l, p 1-8

ISSN 1391-586X: © 2008 Published by Eastern University, Sri Lanka.

Effect of a high dose of Sri Lankan black tea brew(Camellia sinensis) on body weight, liver and kidney

functions in rats

W.D. RatnasooriyaandT.S.P. Fernando

Department of Zoology, University of Colombo, Colombo 03, Sri Lanka.

Abstract,

The aim of this study was to examine general, hepatic and renal toxicities with chronicdaily administration of Sri Lankan black tea (Camellia sinensis L., Family Theaceae).This was tested in rats using black tea brew (BTB) made from Sri Lankan high grownDust grade No: 1 black tea. Either a single heavy dose of BTB (501 mg/ml, equivalentto 9 cups) or water (control) were orally administered to two groups of rats (n = 9/group) daily for 8 weeks. These rats were observed daily for overt signs of clinicalto\icity. Blood samples were collected at two weeks intervals and levels of serum proteins,GOT, GPT, creatinine, urea, Na', K', and Na'/K" ratio were determined. Body weightsof these rats were determined fortnightly and food intake were noted. The results showthat BTB administration did not induce any overt signs oftoxicity or produced significant(p > 0.05) change in any of the serum parameters investigated. On the other hand, asignificant (p < 0.05) weight loss (6.6 - 10.4%) was evident in BTB treated rats after 2weeks. It is concluded that chronic heavy consumption of Sri Lankan black tea appearsto be non toxic to liver and kidney but it suppresses the body weight of a rats.

Short running head: Sri Lankan black tea and toxicity

Key words: Camellia sinensis, liver toxicity, renal toxicity, body weight, Sri Lankan tea,black tea

Author of correspondence: Professor W.D. Ratnasooriya,e-mail: wdr@zoology.cmb.ac.lk

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1. Introduction

Most people enjoy tea on a daily basis. Tea is the second most consumed beverage in theworld at present. It is estimated that globally 3-5 billion cups, glasses or bowls of tea consumeddaily at present. Tea is typically produced from freshly harvested tender shoots comprisingtwo or three of topmost immature leaves and the bud of Camellia sinensis L. plant (Family:Theaceae) [ 1 ]. Depending on the manufacturing technique there are three main types ofteas; black (fully aerated or fermented), green (non aerated or unfermented) and oolong(partially aerated or semifermented).

Of these types, black tea accounts for about 78% of world tea production and about 80%of global tea consumption. It is of interest to note that Sri Lankan tea is drunk in more than125 countries and accounts for 20% of the global tea consumption [2]. Although there is ahigh consumption of Sri Lankan black tea no studies are conducted to investigate its toxiceffects with long term consumption. Black tea contains a large variety of chemicals constituentssuch as flavonoids (catechins, theaflavins, thearubigins, and flavonols), caffeine, amino acids,volatiles, vitamins and minerals [1,3]. In addition, it may also be contaminated with pesticidaland weedicidal residues. Therefore, a possibility exists that heavy daily consumption ofblack tea brew (BTB) chronically could produce toxic effects.

The aim of this study was to examine general, hepatic and renal toxic effects of Sri Lankanblack tea with a heavy chronic daily administration. This was tested in rats using high grownDust grade No: 1 Sri Lankan black tea. The dust grade was selected is the most widelyconsumed type of tea by Sri Lankan tea drinkers.

2. Materials and Methods

. - • '2.1. Animals

Laboratory bred healthy adult male Wistar rats (weighing 275-300 g) purchased fromMedical Research Institute, Borella, Sri Lanka were used. They were kept understandardized animal house conditions (temperature: 28-31 °C, photoperiod: approximately12 hours of light per day, relative humidity 50-55%). They had free access to pelleted food(contents; 19.5% proteins, 7.5% oil, 4.5% fiber, 7.9% ash, 0.48% methylamine, 0.9%calcium and 0.7% phosphorus) (Ceylon Grain Elevators, Colombo, Sri Lanka) and tapwater. All animal experiments were conducted in accordance with the internationally acceptedlaboratory animal use and care (based on Helsinki convention) and guidelines and rules ofthe Faculty of Science, University of Colombo, for animal experimentation.

W.D. Ratnasooriya and T.S.P. Fernando

2.2. Source of tea

Two or three topmost immature leaves and buds of C. sinensis plants plucked from theplantation of St. Coombs tea estate of the Tea Research Institute, Talawakelle, Sri Lanka(1382 m above sea level: high grown) in August 2005 was used to process Dust grade No:1 black tea by orthodox-rotovane technique at the estate factory. The tea sample was pure,unblend and typical to the grade as confirmed by sieve analysis, organoleptic profile, andphysical and chemical analysis. Tea samples were packed in triple laminated aluminium foilbags (1 kg each) and stored at - 20°C until use.

2.3. Preparation of black tea brew (BTB)

BTB was made according to ISO standards [4]: adding 2g of black tea to 100ml water andbrewing for 5 min. This contains 43.7% (w/w) tea solids in water [5]. Based on this data, adose of 501 mg/ml of BTB in 2 ml was made by adding 8g black tea to 20 ml boiling waterand brewing for 5 min. In human terms this concentration is equivalent to 9 cups of tea(1 cup =170 ml).

2.4. Investigation of toxic effects following chronic administration

Eighteen rats were randomly divided into two groups (n = 9/group) and were cagedindividually. One group was orally administered with 501 mg/ml of BTB and the other with2 ml of water daily at (9.00-10.00 h) for 8 weeks. These rats were observed daily (2-3 hfollowing administration) for overt sings oftoxicity (diarrhoea, jumping, restlessness, salivation,rhinorrhoea, lachrymation, chewing jaw movements, potosis, squinted eyes, writhing,convulsions, tremors, yellowing of fur, loss of hair, ataxia, rapid rotational movement ofhead, neck and entire body around the spinal axis, pallor of lips, marked impairments offood and water intake, lethargy and sleepiness), stress (fur erection and exopthalmia),behavioural abnormalities (such as impariment of spontaneous movement, climbing, cleaningefface and ataxia, rolling and other postural changes) and aversive behaviours (biting andscraching behaviour, licking at tail, paw and penis, intense grooming behaviour orvocalisation).Every two weeks during the study period, blood (1.5 - 2.0 ml) was collected from the tailsof these rats under mild ether anaesthesia using aseptic precautions. The blood was allowedto clot at room temperature (28 - 30 °C) and centrifuged at 3200 rpm for 5 min. The serumwas separated. Serum protein, Glutamic-Oxaloactic Transaminase (GOT) (EC 2.6.1.1),Glutamic-Pyruvic Transaminase (GPT) (EC 2.6.1.2), creatinine and urea levels were

JSc- EUSL(2008) Vol.5 No.l, p 1-8

determined using Randox kits (Randox Laboratories Ltd., Co., Antrium, UK) and aspectrophotometer (Jasco V560, Jasco Corporation, Tokyo, Japan) as per manufacturesinstruction (wave length for SGOT, SGPT, protein and urea -546 nm; for creatinine- 492nm). Serum Na+ and KT levels were determined by flame photometrically (Compact atomicabsorption spectrometer, GFS Scientific Equipment Pvt. Ltd., Sydney, Australia). The bodyweights of these rats were also determined 15-30 min before blood collection using anelectronic balance (MP 6000, Chyo Balance Corp, Tokyo, Japan).

*

2.5. Statistical analysis

The data are expressed as mean ± standard error of mean (SEM). Statistical comparisonswere made using Mann-Whitney U-test. Aprobability level of 0.05 or less was consideredas significant.

3. Results

Chronic administration (8 weeks) of 501 mg/ml of BTB did not induce any overt signs oftoxicity, stress or aversive behaviors. Further, as shown in Table 1, the BTB treatment alsodid not significantly (p > 0.05) change the serum proteins, GOT, GPT, creatinine, urea, Na+,K+ levels and serum Na+/K+ ratio. In contrast, BTB treatment caused a significant(p < 0.05) impairment in the body weight (Figure 1) from the second week (6.6 -10.4%)although there was no apparent reduction in food intake. This effect on body weight wastime-dependent (r2 = - 0.87; p < 0.05). However, the animals were active and did notappear lethargic and morbid. Further, no mortality was evident during the study period.

4. Discussion

This study examined the general toxicity (in terms of overt clinical signs), hepatotoxicity (interms of SGOT, SGPT and serum proteins) and renotoxicity (in terms of serum creatinine,urea, Na+, K+ and Na+/K+ ratio) following chronic (8 weeks) administration of a heavydose of BTB made from Sri Lankan high grown Dust grade NO: 1 black tea. The doseselected was 501 mg/ml/day which is equivalent to 9 cups/day. In Sri Lanka, drinking 3cups of tea a day is usually considered as normal and consumption of 10 cups per day isgenerally regarded as heavy [ 1 ]. The results show that chronic administration of a high doseof Sri Lankan BTB dose not induce general toxicity, renotoxicity or hepatotoxicity in rats. Asimilar result may be expected in humans but this needs further investigations with humansubject; five cases of liver toxicity have been reported recently with consumption of a tea

W.D. Ratnasoorlya and T.S.P. Fernando

beverages [6]. This is a novel and an encouraging finding for Sri Lankan black tea as itaccounts for 20% of the global tea consumption [2]. On the other hand, BTB induced aquick reduction in body weight. Further, this reduction in body weight was not drastic andprogressed gradually. This is also an important finding which could have a clinical benefit,especially, in obesetic states. Black, oolong [5] and green tea [8] are claimed to be antiobeseticand promote weight loss [7,9,10]. The weight loss in this study was unlikely to be due tosuppression of food intake as there was no apparent reduction in feeding. However,epigallocatechin but not related catechins of green tea is reported to reduce food intake ofrats [11]. Further, the BTB treated rats were not lethargic and morbidid and therefore thereduction in weight may not be due to toxicity. In contrast, BTB induced weight reductioncould be mediated via raising of metabolic rates and promotion of fat oxidation [10,12].Such an action can be mediated [ 10] by caffeine and other flavonoids present in tea [ 1,3].Drinking of green tea has been shown to lower body weight by increasing thermogenesis[10,13]. Such a mode of action is possible in this study as well.In conclusion, this study shows that Sri Lankan black tea dose not induce overt signs oftoxicity, renal toxicity or hepatic toxicity when consumed daily at a high dose level for a longperiod (upto 8 weeks) in rats. However, the treatment produced a weight loss, which is anencouraging finding of clinical importance.

Acknowledgement•

This investigation received financial support from the National Science Foundation undergrant number NSF/Fellow/2005/01.

References

[1] W.W. D. Modder and A. M. T. Amarakoon (2002). Tea and Health, Tea ResearchInstitute of Sri Lanka, Talawakelle, Sri Lanka, pp. 1-147.

[2] Anonymous (2004). Sri Lanka Tea Exporters Directory, Sri Lanka Tea Board,Colombo, Sri Lanka, pp. 3-6.

[3] D.A. Balentine, S.A. Wiseman and L.C.M. Bouwens (1997). The chemistry of teaflavonoids. Critical Reviews in Food Science and Nutrition 37, 693-704.

[4] Anonymous (1980). Tea-Preparation of liquor for use in sensory tests: ISO3130:1532 International Organization for Standardization, Geneva Switzerland,pp. 1-4.

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JSc- EUSL(2008) Vol.5 No.l, p 1-8

[5] J. R. A. C. Jayakody and W.D. Ratnasooriya (2008). Blood glucose level loweringactivity of Black tea brew Camellias sinensis in rats. PharmacognosyMagazine (in press).

[6] M. Jimenez-Saenz and M.C. Martinez-Sanchez (2007). Camellia sinensis livertoxicity. Journal ofHepatology 47,297

[7] H. Chi-Tang, H. Mou-Tuan. and L. Jen-Kun (2006). Health promotingproperties of black tea. www.worldnutra.com. (accessed on 12/05/2007).

[8] M. W. L. Koo, and C. H. Cho (2004). Pharmacological effects of green tea ongastrointestinal system. European Journal of Pharmacology, 500,177-185.

[9] G.T. Mustata, M. Rosca, K.M. Biemel, O. Reihl, M. A. Smith, A. Viswanathan,C. Strauch, Y. Du, J. Tang,T.S. Kern, M.O. Lederer, M. Brownlee, M.F. Weissand V.M. Monnier (2005). Paradoxical effects of green tea (Camellia sinensis)and antioxidant vitamins in diabetic rats. Diabetes. 54,517-526.

[10] H. Wolfar (2006). Herbal/Plant Therapies: Green tea. www.eurekalert.org/pubjreleases. (accessed on 25/06/2007).

[11] Y.H. Kao, R.A. Hiipakka and S. Liao (2000). Modulation of endocrine systemsand food intake by green tea epigallocatechin gallate.Endocrinology. 141, 980-987.

[12] Anonymous, (2005). Potential effects of tea on health www.en.wikipedia.org/wiki/potentia (accessed on 12/08/2007).

[13] S.J. Bell and G.K. Goodrick (2002). A functional food product for themanagement of weight. Critical Reviews in Food Science andNutrition 42, 163-178.

Table 1: Effect of chronic oral adminis t ra t ion of 501 m g / m l of black tea brew of Camellia sinensis on someserum parameters of rats (mean ± SEM; n = 9)

Parameter

Total proteins (mg/ml)

Serum GOT (11 /L)

Serum GPT (U/L)

Urea (mg/ml)

Creatinine (mg/ml)

Na+ (ppm)

K + ( p p m )

Na+/K+ ratio

Dose

Control (water)

BTB (501 mg/ml)

Control (water)

BTB (501 mg/ml)

Control (water)

BTB (501 mg/ml)

Control (water)

BTB (501 mg/ml )

Control (water)

BTB (501 mg/ml)

Control (water)

BTB (501 mg/ml)

Control (water)

BTB (501 mg/ml)

Control (water)

BTB (501 mg/ml)

Pre t r ea tmen t

6.83 ± 0.008

6.82± 0.002

33.4 ± 0.02 '

33. 5 ± 0.02

10.65 ± 0.03

10.98± 0.05

31.6 ± 0.11

32.3 ± 0.70

0.73 ± 0.002

0.73 ± 0.003

7086. 8 ± 1.7

7082. 8 ± 4 . 8•

286. 89 ± 0.75

285. 67 ± 1.47

24 .70± 0.09

24 .72± 0.08

D u r i n g t r ea tmen t

2 Weeks6.85 ± 0.008

6.88± 0.006

33. 8 ± 0.02

34. 2 ± 0.04

10.61 ± 0.06

10.96± 0.05

31.8 ± 0.11

32.3 ± 0.70

0.75 ± 0.002

0.75 ± 0.001

7083. 7 ± 3.5

7084. 2 ± 2.3

286.11 ± 0.48

285. 89 ± 0.70

24.75 ± 0.1

24.78 ± 0.2

4 Weeks6 .86± 0.005

6.87 ± 0.004

35.0 ± 0.02

35. 5 ± 0.05

11.35 ± 0.02

11.24 ± 0.05

32. 9 ± 0.09

32. 8 ± 0.05

0.78 ± 0.03

0.78± 0.003

7084. 9 ± 0.8

7084. 0 ± 3.3

286.33 ± 0.53

287. 00 ± 0.58

24.75 ± 0.01

24.77 ± 0.3

6 Weeks6. 87 ±0 .001

6.77± 0.003

36. 2 ±0 .07

36. 4 ± 0.07

12.00 ± 0.02

11.21 ± 0.03

33.1 ± 0.15

34.5 ± 0.14

0.81 ± 0.002

0.82 ±0.002

7081. 4 ± 4.6

7082.1 ± 3.7

285. 67 ± 0.90

286. 22 ± 0.62

24.78 ± 0.08

24.76 ± 0.02

8 Weeks6.91 ± 0.001

6.86± 0.002

38.2 ± 0.10

38. 9 ± 0.06

12.60 ± 0.06

12. 5 ± 0.01

33.5 ± 0.15

34.0 ± 0.20

0.83 ± 0.001

0.85± 0.003

7084.9 ± 4.2

7088.9 ± 2.0

286. 56 ± 0.56

285.22 ± 0.64

2 4 . 7 2 ± 0.1

2 4 . 7 4 ± 0.2

>3a38

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